package com.fz.us.admin.base.bean.search.projection;

/**
 * 查询 - 参数 - Projection 帮助类
 * ============================================================================
 * 版权所有 2016 。
 *
 * @author fallenpanda
 * @version 1.0 2016-07-13 。
 * ============================================================================
 */
public class ProjectionHelp {

    /**
     * 无
     */
    public static Projection none() {
        return ProjectionNone.none();
    }

    /**
     * 行数
     */
    public static Projection rowCount() {
        return ProjectionRowCount.rowCount();
    }

    /**
     * 行数
     */
    public static Projection count(String field) {
        return ProjectionCount.count(field);
    }

    /**
     * 行数
     */
    public static Projection countDistinct(String field) {
        return ProjectionCount.countDistinct(field);
    }

    /**
     * 最大值
     */
    public static Projection max(String field) {
        return ProjectionAggregate.max(field);
    }

    /**
     * 最小值
     */
    public static Projection min(String field) {
        return ProjectionAggregate.min(field);
    }

    /**
     * 平均值
     */
    public static Projection avg(String field) {
        return ProjectionAggregate.avg(field);
    }

    /**
     * 和
     */
    public static Projection sum(String field) {
        return ProjectionAggregate.sum(field);
    }

}
